Brominated flame retardants are used as additives in many engineering plastics to meet current safety standards for flammability. These plastics are commonly used in the industrial and consumer electronics markets for applications such as plastic housings, battery packages, printed circuit boards, adhesives, shrink tubing, etc. Most brominated flame retardants consist of at least one aromatic ring and they all carry a high number of bromine atoms. While they substantially reduce the flammability characteristics of these polymers, brominated flame retardants are regarded as an environmental hazard because they are toxic and/or carcinogenic. They contribute to the formation of dioxins when incinerated or exposed to intense heat during recycling. The various types of flame retardants have different levels of toxicity or contribute differently to the formation of dioxins. Legislation in the European Union (EU) has been enacted to reduce the level of brominated flame retardants in the environment. The Restriction of certain Hazardous Substances (RoHS) act has targeted brominated flame retardants in electronic devices, and provides an outright ban on two types of brominated flame retardants, polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE).
In order to comply with theses enacted regulations, a method to detect and identify brominated flame retardants in engineering plastics is needed. Such a method should be fast and accurate to enable rapid testing and short turnaround times in keeping with the ‘time to market’ requirements of the global electronics industry. The detection method also needs to be highly cost effective and it should not have any adverse impact on the environment by using other hazardous substances in the detection procedure, and it should be easy to use.
Historically, a number of methods have been used in the chemical laboratory to determine the presence of additives in polymers, such as high pressure liquid chromatography (HPLC), gas chromatography/mass spectral analysis (GC-MS), laser thermography, laser plasma emission, x-ray fluorescence, pyrolysis, and infrared (IR) spectroscopy techniques such as multiple internal reflectance (MIR), Raman scattering, and near infrared. Some of these techniques have been used with varying degrees of success in the analysis of brominated flame retardants in polymers. The HPLC detection method, for example, requires a number of sample preparation steps and uses environmentally sensitive reagents. Many techniques require extensive and tedious sample preparation steps which make the determination cumbersome and not amenable to rapid, routine analysis. Others are so inexact as to be of little value in addressing the needs of the RoHS act. A method that rapidly and accurately identifies the presence of brominated flame retardants in polymers would be a valuable addition to the art.